RouterOS/RouterOSAssistant/Core/Networking/SSHHostKeyFingerprint.swift

import Foundation
import NIOCore
import NIOSSH
import CryptoKit

enum SSHHostKeyFingerprint {
    /// SHA256 over the key's SSH wire-format encoding (`NIOSSHPublicKey.write(to:)`) — the
    /// same bytes OpenSSH itself hashes for its `SHA256:...` host key fingerprints.
    static func sha256(of key: NIOSSHPublicKey) -> String {
        var buffer = ByteBuffer()
        _ = key.write(to: &buffer)
        let bytes = buffer.readableBytesView
        let digest = SHA256.hash(data: Data(bytes))
        return digest.map { String(format: "%02X", $0) }.joined(separator: ":")
    }
}